I have a duo therm furnace in my trailer its model 65925.080 .I am having a problem with this furnace .I turn on the thermostat the furnace fan comes on and the fire comes on and the fire shuts off after only a few seconds, the fan keeps going. would it be the board everything else seems ok. i get voltage at the coil that opens the gas valve but it does not stay on more than a few seconds.

 

Welcome to the forums.

Your problem is with the flame sensor area. It could be at the burner or the board. I'm going to look up your mobile furnace and will post further.

 

Hi thanks for the information ,Please let me know what you can find out .I need the help

 

Has the unit been working fine and just started having the problem ?
Has any of the wiring been changed to the the heater ?
How old is the unit ?

The following is a link to the DSIS service guide. Download and save it.

Page 2 is the block diagram. At the top you'll see electrode assembly. The black wire connects to the flame sensor rod. The orange wire connects to the spark electrode. You may need to remove this ass'y from the furnace to clean the flame sensor rod. If you have a microamp setting on your test meter you can check the current flow in the black wire before removing the ass'y.



Bryant rv/docs2/docs/659/ODSI.pdf
As always.... thanks to Chris Bryant for hosting these manuals as they are hard to get and he does it for free.

 

we just bought this trailer and just tried the furnace and found this problem. It does not seem to be tampered with .I have checked the ignition electrodes and they are good and the ceramic insulators are in good condition. I had an ohm meter on the sensor wire to the end of electrode and its reading that its a dead short so the wire is good, I will double check the spark gap and the distance from the electrode to the burner head I will also double check the sensor electrode height from the burner head. If it does not work then it should be the board . Thanks for all this information you have been a real help.

 

Steel wool the flame rod first. It may look OK but the thin film of oxidation will prevent the millivolt current from registering at the board.

 

Has high limit switch been checked?